MSX2+ YJK Colors | MSX-BASIC 3.0+ (MSX2+/turbo R) / z88dk https://msxjpn.jimdofree.com/%E3%83%97%E3%83%AD%E3%82%B0%E3%83%A9%E3%83%A0/yjk-%E8%A1%A8%E7%A4%BA/

yjkcolor.c

/*
 MSX2+ YJK colors | MSX-BASIC 3.0+ / z88dk
 Copyright (c) 2019 Keiichi Shiga (BALLOON | FU-SEN)
 The MIT License (MIT) - https://mit.balloon.net.eu.org/#2019

 zcc +msx -lndos -create-app -subtype=disk -bn yjkcolor yjkcolor.c
 --> BLOAD"YJKCOLOR.MSX",R
*/

void chgclr(char forclr, char bakclr, char bdrclr)
{
#asm
    ld   ix,0
    add  ix,sp
    ld   a,(ix+2)       ; BDRCLR
    ld   (0f3ebh),a
    ld   a,(ix+4)       ; BAKCLR
    ld   (0f3eah),a
    ld   a,(ix+6)       ; FORCLR
    ld   (0f3e9h),a
    ld   ix,0111h       ; CHGCLR
    call 015fh          ; EXTROM
#endasm
}

void chgmdp(char mode)
{
#asm
    ld   a,l            ; mode
    ld   ix,01b5h       ; CHGMDP
    call 015fh          ; EXTROM
#endasm
}

void screen12()
{
#asm
    ld	 hl,0fffah      ; rg25sa
    res  4,(hl)
    set  3,(hl)
    ld   a,(hl)
    ld   b,a
    ld   c,25           ; R#25
    call 0047h          ; WRTVDP
#endasm
}

void nstwrt(int addr)
{
#asm
    ld   ix,0
    add  ix,sp
    ld   l,(ix+2)       ; addr
    ld   h,(ix+3)
    call 0171h          ; NSTWRT
#endasm
}

void out(char reg, char data)
{
#asm
    ld   ix,0
    add  ix,sp
    ld   b,(ix+2)       ; data
    ld   c,(ix+4)       ; reg
    out  (c),b
#endasm
}

int gttrig(char num)
{
#asm
    ld   a,l            ; num
    call 00d8h          ; GTTRIG
    ld   l,a
    ld   h,0
#endasm
}

void main()
{
    int c=15;

    chgmdp(8);
    screen12();

    chgclr(255, 0, 0);

    c=c<<3;

    nstwrt(0);
    for (int y=0; y<212; y++) {
        for (int x=0; x<256; x+=4) {
            int j=x*64/256-32;
            int k=y*64/212-32;

            out(0x98, c|k&7);
            out(0x98, c|k>>3&7);
            out(0x98, c|j&7);
            out(0x98, c|j>>3&7);
        }
    }
    while (! gttrig(0));
}